Answer: So you know which kinds of information will best persuade your readers and also they can have a good time reading your book and not saying its boring if u worked really hard on it and so u can can spel out the word to people so u can sell copys and You need to say things that appeal to them. If you have a group of twelve year olds, you probably aren't going to talk the same way to them as you would to a group of thirty year olds.
Because no one has ever really seen it before and there is no evidence of there ever being a kind of creature in existence like the Loch Ness monster, which is supposedly a dinosaur-like swan/snake by it's description.